The 802.16 WiMAX technology is a next-generation wireless broadband communication technology providing wide-area outdoor services with more extended functions and coverage than Wi-Fi (802.11b/g), which is a wireless communication technology providing indoor services around a hot spot. While the coverage of Wi-Fi may be about 30 to 200 m and the transmission rate thereof may be no more than 4 to 11 Mbps, the coverage of WiMAX can be extended for up to 10 km and the available transmission rate thereof can be 40 Mbps. This offers a substantial technical advantage.
Conventionally, the WiMAX network includes a user equipment (UE) and a base station (BS). The UE is used for a subscriber to access the WiMAX network. The BS transmits control signals and data signals to the UE and receives control signals and data signals from the UE. A system management station in the WiMAX network transmits primary setting data to all the BSs in the WiMAX network. The primary setting data includes parameters for operating the BS. The BS stores the primary setting data and periodically broadcasts the same to the UEs in a service area of the BS. The primary setting data includes data related to a handover from one BS to another BS. The UE figures out handover information (HI) based on the primary setting data. The HI includes the timing of the handover and the target of the handover. The UE performs the handover based on the HI.
Conventionally, the UE performs the handover from one BS to another BS based on the HI. For this, the BS broadcasts the HI of all neighboring BSs to the UE. And the UE stores the HI of all the neighboring BSs.
The WiMAX network further includes a plurality of femto base stations in the service area of the macro base station. The plurality of femto base stations has a narrower service coverage area than that of the macro base station. Therefore, the WiMAX network with the plurality of femto base stations can resolve the cell tower traffic and guarantee good signal intensity in bad signal conditions. Though the service coverage of the femto base stations is narrow, the femto base stations operate in the same manner as the macro base station. Thus, not only are handovers among the macro base stations needed, but handovers between the macro base station and the femto base station are also needed.
When the method of performing handovers among the macro base stations is applied to the handover between the macro base station and the femto base station, it may be difficult to manage the data for the handover. In the service area of the macro base station, a plurality of femto base stations may be present. For applying the conventional method of the handover among the macro base stations to the handover between the macro base station and the femto base station, the macro base station may broadcast information for all the femto base stations in the service area as the primary setting data to the UE, and the UE may store the information for all the femto base stations. Thus, a data management load in the macro base station can be too heavy since the information for all the femto base stations in the service area of the macro base station should be managed and a huge amount of data for handover should be transmitted to the UE. Therefore, it may be impractical for the macro base station to manage and transmit the data for handover.